Where birds are rare or fill the air : the protection of the endemic and the nomadic avifaunas of the Karoo

Doctoral Thesis


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University of Cape Town

The primary objectives of this study were to assess the protected status of birds in the Succulent and Nama-Karoo, and to identify areas, using a GIS approach, where new protected areas could be established. The Karoo sensu lato lacks a distinctive avifauna, but is rich in species. A total of 407 bird species has been recorded in the Succulent and Nama-Karoo, of which 294 species are considered typical of the region. The Karoo is not particularly rich in bird species endemic to the region, and all Karoo endemic species occur in both biomes. The Nama-Karoo has an unusually high species richness of nomadic birds, and both the Succulent and Nama-Karoo have an unusually high species richness of larks (Alaudidae) compared with other biomes. The Succulent and Nama-Karoo have stochastically low annual rainfall and generally low above-ground primary production. Rainfall is often highly localized and varies annually in amount and timing. The variability of the rainfall and long dry spells or severe droughts create a mosaic so that high and low resource areas occur as patches in the landscape. Resident species of birds tend to maintain low densities and wait for rainfall events, whereas nomadic species search for high resource patches scattered in time and space, so that their respective densities likewise vary temporally and spatially. Compared with other biomes in southern Africa, there is a high species richness of nomadic birds in the Karoo. The small nomadic larks are most common in areas of perennial and annual desert grasses, and they feed on grass seeds, whereas resident granivorous birds tend to feed on the seeds of forbs and shrubs. Clutch sizes of the nomadic larks birds are small, apparently selected for by the need for a short breeding cycle.

Bibliography: p. 231-256.